Hi all,
I've been muddling through lots of examples - not to mention pestering SurferTim and zoomkat (thanks guys)- to figure out the Ethernet shield.
Fellow member boga then posted a link to this tutorial. I would urge anyone trying to figure out the E'net shield (and SD card) to start there.
Thanks boga!
Jim
Just downloaded the individual pages. (19 total! EEK! 
) I've done a few ethernet experiments with the Ethernet shield (non-R3, and an even older one w/o the SD card), being fed from a cheap WiFi router, and talked to from the laptop via WiFi. (one fair warning to others, Not every router defaults to 192.168.1.1 some are 192.168.2.1 . Be sure to set your code accordingly to the router.)
One thing I'm having trouble with, and others have as well, the +5V regulator on the board (On the Duemilinova & the Uno) get real hot using these shields.. The W5100 seems to draw an enormous amount, going from the +5V down to 3.3V. (the shield's on-board 3.3V regulator.) Is it possible to maybe draw the +5V from another source? The newer w/SD also draws +5V through the ICSP socket, but the older one has no ICSP.. what I'm thinking of, is running a wire from the power supply (a modified 200W ATX supply) to the +5V, Isolating that pin from the header of the Arduino. But.. that ICSP pin is the stumbler... Would I need to isolate that one as well?
Stephen
Is it possible to maybe draw the +5V from another source?
When I tried to power my Duemilinova and Ethernet shield from 12v via the onboard barrel jack, the voltage on the board was 8v+. I then successfully externally powered the board via a 7805 regulator chip connected to the board 5v pin.
Powering the Arduino with the 5v pin, especially the Mega, can cause damage to the board if the usb is also providing 5v power. Here is the warning from the Uno page. The Mega has the same warning.
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
You should read this thread also...
http://forum.arduino.cc/index.php?topic=82046.0
...and especially this post from Arduino team member David Cuartielles
http://forum.arduino.cc/index.php?topic=82046.msg758170#msg758170